The purpose of this service contract is to provide a facility for the storage, monitoring and distribution of the serum, plasma, and urine collected from the double-blind, randomized clinical trial of supplemental calcium for the prevention of preeclampsia (CPEP) during pregnancy from five clinical centers. It is expected during a two year period that 4,500 pregnant women will be enrolled in the study. Blood and urine specimens will be collected from study participants at baseline and early (26-29 weeks gestation) and late (26 weeks gestation) in the third trimester of pregnancy. Samples will also be collected at the time of diagnosis of preeclampsia and related conditions. Laboratory analyses will be performed at laboratories selected by the NICHD on the samples from selected study participants soon after the termination of pregnancy.